1. Field of the Invention
This invention relates to closure fastening devices, and more particularly, to interlocking closure fastening devices having improved occlusion and deocclusion characteristics.
2. Discussion of the Prior Art
Generally, closure fastening devices for use with plastic bags and the like are well-known. In addition, manufacturing methods for closure devices made of plastic material are generally known.
Closure fastening devices for use with plastic bags should be relatively easy to open and close, and also provide a satisfactory seal. However, it has been found that some prior art interlocking closure fastening devices suffer from a tendency of the male and female closure elements to straddle each other and to not occlude during attempted occlusion as opposed to a normally occluded position. Such a non-occluded, and also straddled condition of the male and female closure elements on a plastic bag precludes occlusion of the closure elements and results in the bag contents not being securely contained within the bag. Therefore, a need exists to provide more positive guidance of the opposing closure elements such that the elements engage more repeatedly into the normally occluded condition, and that the elements be inhibited from engaging into a non-occluded and straddled condition.
In addition, prior art interlocking closure fastening devices suffer from lack of significant controlled separation, i.e., deocclusion characteristics. The controlled separation characteristic of a closure device may be described as the ability to resist opening any further than the initial gap induced by the original opening force of the user. This deficiency in controlled separation manifests itself during opening of a plastic container or bag and is especially troublesome to a user during the closing or sealing operation of the container. More specifically, when plastic bags having closure fastening devices are partially opened, they can continue to open completely with little or no external separating force applied to the fastening devices. Such a characteristic is desirable for opening the plastic bag but presents a disadvantage on closure since the user often desires to expel the preponderance of air from the bag prior to sealing. This is most desirably accomplished if the major portion of the fastening device is interlocked, and only a small aperture remains for expelling most of the residual air from the bag before accomplishing the final closure and sealing. Thus, there is a need to provide closure fastening devices which have controlled separation characteristics so that a partially occluded bag will not deocclude, except to the extent that the user may further apply an opening force.
It would also be desirable to provide interlocking closure fastening devices having controlled separation characteristics while not adversely affecting the force required to deocclude the outside hooks of the interlocked closure fastening device, i.e., the initial opening force, so that it is still relatively easy to open from the outside. Likewise, it would further be desirable to provide interlocking closure fastening devices having controlled separation characteristics while maintaining the force required to deocclude the inside hoods of the interlocked closure fastening device so that it will be relatively harder to open from the inside than from the outside in order to provide secure containment of goods in a container or bag equipped with the interlocking closure fastening device.